1. Field of the Invention
The present invention relates generally to decision feedback equalizers and in particular to low-power decision feedback equalizers for communication systems.
2. Background Information
A decision feedback equalizer (DFE) utilizes decisions on data symbols that have been previously transmitted to reduce or eliminate intersymbol interference (ISI) that may be caused by such previously transmitted data symbols.
Building decision feedback equalizers at very high data rates (e.g., greater than 15 Gbit/s) has been a challenge due to the stringent timing requirements in the requisite feedback loops. One approach has been to use multi-tap speculation, leading to sampling the data signal with a number of 2n samplers at given voltage thresholds, and later determining which of the samples to use dependent on the previous symbols. However, to achieve low power, the number of speculated taps n has to be kept as small as possible since complexity grows as 2n.